* {
    margin: 0;
    padding: 0;
  }

  ul li {
    list-style: none;
  }

  main {
    width: 960px;
    height: 500px;
    border-radius: 10px;
    margin: 50px auto;
  }

  main h4 {
    height: 100px;
    line-height: 100px;
    text-align: center;
  }

  .tab {
    width: 900px;
    margin: 0 auto;
    height: 400px;
    border: 1px solid lightsalmon;
    position: relative;
  }

  nav ul {
    overflow: hidden;
  }

  nav ul li {
    float: left;
    width: 100px;
    height: 50px;
    line-height: 50px;
    text-align: center;
    border-right: 1px solid #ccc;
    position: relative;
    cursor: pointer;
  }

  nav ul li.active {
    border-bottom: 2px solid orange;
    z-index: 9;
  }

  #tab input {
    width: 80%;
    height: 60%;
  }

  nav ul li span:last-child {
    position: absolute;
    user-select: none;
    font-size: 12px;
    top: -18px;
    right: 0;
    display: inline-block;
    height: 20px;
  }

  .tabAdd {
    position: absolute;
    /* width: 100px; */
    top: 0;
    right: 0;
  }

  .tabAdd span {
    display: block;
    width: 20px;
    height: 20px;
    line-height: 20px;
    text-align: center;
    border: 1px solid #ccc;
    float: right;
    margin: 10px;
    user-select: none;
  }

  .bd {
    width: 100%;
    height: 300px;
    position: absolute;
    padding: 30px;
    top: 50px;
    left: 0px;
    box-sizing: border-box;
    border-top: 1px solid #ccc;
    font-size: 30px;
  }

  .bd section {
    display: none;
    width: 100%;
    height: 100%;
  }

  .bd section.active {
    display: block;
  }